Senator Conroy has responded by asking Mr Turnbull what advice he gave to former HIH Insurance boss Ray Williams, who was jailed after overseeing what was Australia's biggest corporate collapse.

Mr Turnbull was named in a $500 million damages claim brought by the liquidator of HIH (which was ultimately settled in his favour in 2003).

"You are so desperate that all you can do is smear," Mr Turnbull said in the debate, hosted by technology news website ZDNet.

"You poor fellow... Such a grub, Stephen."

"Malcolm doesn't want to talk about upload speeds because it's like a wooden stake to a vampire," Senator Conroy responded.

Turnbull's network solution to fast broadband will use Telstra's copper telephone lines, which Conroy claims offer only a fraction of the upload speeds possible under Labor's more expensive network, which runs fibre optic cables all the way to homes.

Under the Coalition plan which will deliver fast movie downloads users who want to get the "super" fast speeds to play games, watch movies or run a business will have to pay between $4,000 and $5,000 to have their home connected to the fibre network.

The Coalition's $20 billion NBN runs fibre to cabinets or ''nodes'' on street corners and would then piggyback on Telstra's copper telephone lines to take the data over the last mile to the house. Turnbull claims that there is "no technical barrier to having very high upload speeds".

Fairfax Media said that Labor's $37 billion NBN plan promises that 93 per cent of Australians will get fibre to the premises, which will offer download speeds of as fast as 1 gigabit per second and upload speeds of 400 megabits per second by 2021. The remaining 7 per cent of Australians living in rural and regional areas will get a mix of wireless and satellite technologies.

"The idea that you've got to have everyone on fibre to the premises to have a strong digital economy is nonsense," Mr Turnbull said during the debate.

If the Coalition wins government, Mr Turnbull would instruct NBN Co to guarantee a 25 megabit per second download speed for every Australian household, and if necessary the company would build an extra series of "mini nodes" closer to houses to achieve the speeds, he said.